As you Asking for the Information About the Department of Defence Travel Card Guide of the Citi bank the information is given below

The Designated Billing Office (DBO) is responsible for paying CBAs within Prompt Payment Act time frames. Upon receipt of a proper invoice, the DBO may ease tracking by date-stamping the official invoice (electronic or hard copy), reconciling the account(s) and paying the invoice, less any disputed amounts, under the terms of the GSA Master Contract and the DoD Task Order

Objective

Department of Defense (DoD) Travel Card program. This program is designed to meet the following program objectives:

Reduce paperwork and administrative costs for the Centrally
Billed Travel Card accounts (CBAs) by Citi
Streamline procedures associated with management practices regarding
official DoD travel and official travel-related expenditures
Provide procedural controls and feedback to improve management control
and decision-making regarding Citi


Invoices
Citi will invoice the DBO for CBAs on a frequency designated by the DoD and agreed upon by Citi.

Citi will provide invoicing in either electronic or paper formats, depending upon requirements.

If the DoD selects the EC/EDI invoice option, these invoices will be structured and formatted

in accordance with I-FSS-599, Electronic Commerce—FACNET.